In a company the average salary of male employees is $₹8200$ and that of female employees is $₹7200$. If the average salary per employee is $₹7900$ then the percentage of female employees of the total employees is _____.

If the mode of the observations $4, 2, 3, 3, 3, 2, 2, 4, 2, 4, x, 3, 4, 4, 2, 3, 4$ is $4$, then $x$ cannot be _____.

The mean of $15$ observations is $30$. Two observations $28$ and $38$ are deleted and three observations $33, 39$ and $48$ are included. Find the new set of observations.

The mean of $A, B, C, D, ... X, Y, Z \left(26 terms\right)$ is $a$. Find the value of $\left(A-a\right)+\left(B-a\right)+\left(C-a\right)+\left(D-a\right)+...\left(X-a\right)+\left(Y-a\right)+\left(Z-a\right).$